1. Field
The present application relates generally to the transmission of information over a distribution network, and more particularly, to methods and apparatus for timing synchronization in a communication network based on transitional pilot symbols.
2. Background
Data networks, such as wireless communication networks, have to trade off between services customized for a single terminal and services provided to a large number of terminals. For example, the distribution of multimedia content to a large number of resource limited portable devices (subscribers) is a complicated problem. Therefore, it is very important for network administrators, content retailers, and service providers to have a way to distribute content and/or other network services in a fast and efficient manner and in such a way as to increase bandwidth utilization and power efficiency.
In current content delivery/media distribution systems, wide area and local area real time and non real time services are packed into a transmission frame and delivered to devices on a network. For example, a communication network may utilize Orthogonal Frequency Division Multiplexing (OFDM) to provide communications between a network server and one or more mobile devices. This technology provides a transmission frame that is packed with services to be delivered over a distribution network as a transmit waveform.
One problem associated with OFDM-based broadcast systems is that of time tracking synchronization. For example, timing synchronization in such systems is based on time-domain channel estimates. Typically, the length of the channel estimate used for data demodulation is shorter than twice the maximum expected delay spread. Using such channel estimates for time tracking synchronization may result in timing ambiguities due to the aliased nature of the time-domain channel estimate. As a result, the transmitted services may not be accurately decoded at receiving devices.
Therefore it would be desirable to have a system that operates to provide accurate time tracking synchronization that is more reliable and less prone to timing ambiguities.